The Pope's chief astronomer says that life on Mars cannot be ruled out.

Writing in the Vatican newspaper, the astronomer, Father Gabriel Funes, said intelligent beings created by God could exist in outer space.

Father Funes, director of the Vatican Observatory near Rome, is a respected scientist who collaborates with universities around the world.

The search for forms of extraterrestrial life, he says, does not contradict belief in God.

The official Vatican newspaper headlines his article 'Aliens Are My Brother'.

C. S. Lewis, an Oxford and Cambridge professor, who was an Anglican and a Christian apologist wrote a science fiction trilogy that included life on other planets. One of the books had characters analogous to Adam and Eve, who lived on another planet and were tempted by a Tempter.

I don't think most orthodox (small "o") Christians would say that the Bible contains descriptions of aliens; however, there are guests on "Coast to Coast" (a middle-of-the-night radio show which specializes in talking about aliens, ghosts, conspiracies, Bigfoot, etc.) who claim to be "Christian" and say that angels are really space aliens and that the Nephalim (very briefly mentioned in Genesis in passages which are unclear) were space aliens.

In my opinion, the Bible is silent on this question. I doubt that there are space aliens; however, if one showed up on my doorstep, it wouldn't shake my faith in God.

__________________"Be of good comfort, Master Ridley, and play the man! We shall this day light such a candle, by God's grace, in England, as I trust shall never be put out."
--Hugh Latimer, October 16, 1555

I've heard people justify aliens through the jacobs ladder aspect of the bible, personally I dont know, I would say that the bible is pretty unclear, but then at the same time you could say that the bible is unclear about dinosaurs, and yet I have heard peopel claim that leviathon was a giant reptile, and that in turn would have been dinosaurs.

Dose the bible say anything about them?No.
Is it possible that god exists and aliens do as well?Yes.
with all the stars and infinite galaxies is it possible that god made alien lifeforms? Sure, but only those who get to Heaven will ever truly know the wonders of the God's infinite creation.

There's only one verse in the Bible that even implies that life is possible outside of the planet Earth; but you have to go back to the original Hebrew text since many translators actually change the text to erase that implication. Deuteronomy 30:4 (NKJV)
"If any of you are driven out to the farthest parts under heaven, from there the LORD your God will gather you, and from there He will bring you."

The "farthest parts under heaven" is more accurately translated as "farthest parts of heaven" or "farthest parts of the sky."

I have a Jewish Torah which translates Deuteronomy 30:4 as:
"If any of thine that are dispersed be in the uttermost parts of heaven, from thence will the LORD thy God gather thee, and from thence will He fetch thee."

The word used for "heaven" here is "samayim" which can also be translated as "sky." From an ancient Jewish perspective, heaven or sky would be a reference to what we consider outer space. However, considering that most Bible translations predate space travel, it's understandable as to why the translators would feel the need to change that sentence.

BUT, this is more of a reference to the human race's ability to leave the planet Earth. It has nothing to do with alien life, but that really just depends on how you define "alien life." The basic meaning of the word "extraterrestrial" simply refers to a being that did not originate on the planet Earth. In that general sense of the word, then you could use extraterrestrial to refer to all angels, demons, Satan and even GOD Himself (the word doesn't imply that an origin is required. Just that, if the being has an origin, it is not on Earth). So in that sense, you could say that the Bible is all about extraterrestrial life.

Ellie Arroway:I'll tell you one thing about the universe, though. The universe is a pretty big place. It's bigger than anything anyone has ever dreamed of before. So if it's just us... seems like an awful waste of space. Right? -quote from the movie Contact

The Universe:
100 billion galaxies in the observable universe
100 billion stars (solar systems) within each galaxy
Let's use our solar system as an estimate - 9 planets in our solar system
100 billion x 100 billion x 9 = 90,000,000,000,000,000,000,000 planets in the observable universe.
Earth is the ONLY planet in the universe with life, or even intelligent life?